Add pin for fmt in conda (#2223)

#### Reference Issues/PRs
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#### What does this implement or fix?
There is a new version of `fmt `that is having problems linking to
`spdlog`.
The proposed fix is to pin `fmt `to the previous stable version.

#### Any other comments?

#### Checklist

<details>
  <summary>
   Checklist for code changes...
  </summary>
 
- [ ] Have you updated the relevant docstrings, documentation and
copyright notice?
- [ ] Is this contribution tested against [all ArcticDB's
features](../docs/mkdocs/docs/technical/contributing.md)?
- [ ] Do all exceptions introduced raise appropriate [error
messages](https://docs.arcticdb.io/error_messages/)?
 - [ ] Are API changes highlighted in the PR description?
- [ ] Is the PR labelled as enhancement or bug so it appears in
autogenerated release notes?
</details>

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Author: G-D-Petrov

environment_unix.yml

@@ -36,7 +36,7 @@ dependencies:
   - azure-core-cpp
   - azure-identity-cpp
   - azure-storage-blobs-cpp
-  - fmt
+  - fmt <11.1
   - folly==2023.09.25.00
   - unordered_dense
   # Vendored build dependencies (see `cpp/thirdparty` and `cpp/vcpkg.json`)